Thread: Difference between linux and unix

What exactly is the difference between UNIX and Linux? Are they related at all?

Basically, at this point, "UNIX" is used to refer to a type of OS (it technically still has active lineage from the SCO group in the various BSD sources), while Linux is a specific (new from the ground up) implementation of a UNIX-like system. As such, there are many "unixes", "unices"... whatever, like HP-UX, AIX, IRIX, Linux, and even (some consider) Mac OSX. And the really technical answer is that Linux is just the kernel (main part of OS plus drivers) and GNU/Linux is the kernel plus the useful OS tools, but the people who push this answer need to just relax and stop worrying about semantics.

Think of it this way: UNIX is like so-called crushing motorcycles (i.e. similar attributes, similar look, similar operation), Linux is like, say, Harleys (or, again, for the truly fastidious, Linux is the standard 88 or now 96 cubic inch v-twin motor with frame and transmission, GNU is the rest of the bike) since they share many of the same parts but there are many, many different overall styles (otherwise known as distributions).

I hope this explanation clears things up a bit.

In practice, there really is no difference. The same programs are available and will run on both a Linux and the various UNIX machines (BSD, Solaris, AIX, IRIX, etc.) They both have a similar file structure, similar commands, and the like. There are some very minute differences between how some things are implemented, but for the most part, you can interchange the two and you'd never know the difference. Perhaps the biggest user-visible differences in Linux and UNIX are that drivers, such as Ati or NVIDIA display drivers are not interchangeable between Linux and UNIX. Also, Linux is GPL v2 code and the licenses in UNIX range from the BSD license to proprietary licenses.

In principle, Linux and UNIX are their OSes' kernel- the backest of back-end part of the OS that takes system requests and talks to drivers. The Linux and UNIX kernels are of a little different structure and are not related in structure, but accomplish the same function. Richard Stallman and his GNU group wrote the rest of the backend for most UNIX-like OSes. The GNU system tools are slightly tweaked between UNIX and Linux to deal with each individual kernel but provide the same interfaces on the front end to the programs and such- that is why UNIX and Linux seem so similar.